Skip to content

Windows and double glazing

It's true. We like timber windows. We hate plastic.

My house has replacement windows and I want to reinstate the original design. How can I find out what sort of windows it originally had?

The first step is to see whether any original windows remain on the property. There may still be old windows at the back, or in less significant rooms or outbuildings. Neighbouring houses may still have their original windows, which can be copied. Points to note include:

  • the depth of the frame and its relationship to the surrounding masonry
  • the presence and shape of horns
  • the number and proportions of lights in each window
  • the thickness and profile of glazing bars, stiles and sashes

How can I improve heat and sound insulation without replacing my original timber windows?

Well-maintained timber sash windows should not rattle or admit draughts. You can upgrade your existing windows with one of several proprietary draught-stripping systems. Some of these you fit yourself; others are fitted by specialists, many of whom work on a franchise basis. For further information, contact the Draught Proofing Advisory Association (DPAA), PO Box 12, Haslemere, Surrey GU27 3AH. Tel: 44 (0)1428 654011. Fax: 44 (0)1428 651401. Website: www.ceed.org.uk/default.asp. Email: ceedassociation@aol.com

  • Timber shutters provide very good sound and heat insulation, and improve security.
  • Thick, lined and interlined curtains cut down heat loss and draughts very effectively. They can be fitted behind front doors using specially designed portière rods.
  • Secondary glazing (see below) improves insulation without the need to alter the existing windows.

How can I improve the security of my windows?

Contact your local police station to request a visit from the Crime Prevention Officer. The officer will give free advice on home security.

Locksmiths carry a wide range of window locks. The type that uses a steel screw through the meeting rails is less visually intrusive than surface-mounted designs.

What is the difference between double-glazing and secondary glazing?

Double-glazing usually consists of two panes of glass with a gap of about 16 mm between them. The panes are vacuum sealed into a single unit that is fitted into the window frame.

Secondary glazing is an independent system of windows fitted to the inner window frame. The gap between the outer and inner windows is consequently much wider than in sealed double-glazed units. The secondary frames are aligned with the external window frames, to cause the least possible visual disruption. The advantages of secondary glazing are:

  • it does not interfere with the exterior fenestration
  • the bigger the gap between the exterior and interior panes, the better the insulation -- particularly noise insulation
  • it is cheaper than replacing the original windows
  • it is reversible.

Is it possible to fit double-glazing in a traditionally-made timber sash window?

Yes. Most timber sash window specialists can make new windows that incorporate sealed, double-glazed units within traditional timber frames. However, the levels of sound and thermal insulation given by double-glazing can often be matched by draught-proofing original windows, by installing secondary glazing or by using thick curtains or internal shutters.

What style of window is best for a loft conversion in a Victorian house?

New openings in a roof must not damage the roof structure, and must be in scale and in keeping with the rest of the house. Dormers should be sensitively designed, modestly scaled and carefully sited so as not to jar with the existing architecture. This is particularly important on the front elevation, but applies also to the side and rear of the house.

The same care should be taken over the choice and placing of rooflights. The aim should be to use the smallest size and number of rooflights as possible, and to replicate the proportions, glazing bars and profiles of Victorian iron rooflights. Replicas of traditional rooflights are available.

Don't forget also to check our series of booklets on Care for Victorian Houses. Every aspect of Victorian house design and interior decoration is described in detail in The Victorian Society Book of the Victorian House.

© 2014 The Victorian Society
1 Priory Gardens, London W4 1TT. T 020 8994 1019. E (JavaScript must be enabled to view this email address)
Charity No. 1081435. Company No. 3940996. Registered in England. Office as above.

Make a donation to the Victorian Society. Online donations are processed securely by PayPal.